Effect of conservation agricultural and nutrient management practices on castor (Ricinus communis)–sorghum (Sorghum bicolor) cropping system in rainfed Alfisols

A fixed-plot field experiment was conducted during 2010 and 2011 at Hyderabad, to study the effect of conservation agricultural (minimum tillage, crop residue and cover crop) and nutrient management practices (recommended dose of fertilizers, integrated nutrient management, organic nutrient management, fertilizers based on soil test crop response, and customized fertilizers) on the productivity, soil fertility, nutrient uptake and nutrient use efficiency of castor {Ricinus communis (L.)}–sorghum {Sorghum bicolor (L.) Moench} cropping system in rainfed Alfisols. There was no significant difference between the conservation and conventional agricultural practices with reference to yield attributes, seed yield and quality of either castor or sorghum. However, conservation agricultural practices resulted in higher castor equivalent yield, CEY (2.24 t/ha), economic returns (benefit cost ratio 1.72) besides improving soil organic carbon (0.41%) compared to conventional practices (2.081 t/ha of CEY, 1.60 B:C ratio and 0.37% soil organic carbon). Among nutrient management practices, customized fertilizers and fertilizers based on soil test crop response (STCR) resulted in about 18 and 15% increase in castor and sorghum seed yields, respectively compared to recommended dose of fertilizer (RDF). Application of customized fertilizers resulted in the highest system productivity (2.426 t/ha of CEY) followed by STCR (2.403 t/ha of CEY) compared to RDF (2.068 t/ha of CEY). Economic returns also followed trend similar to CEY. Organic nutrient management recorded the highest soil organic carbon (0.42%), soil available N (220 kg/ha) and K (434 kg/ha) compared to the control. Customized fertilizers recorded the highest uptake of nutrients in both castor (64.1–20.6–37.3 kg NPK/ha) and sorghum (118.3–39.3–152.5 kg NPK/ha) compared to RDF. Agronomic efficiency of N, P and K was in general, higher in either STCR or customized fertilizer treatments, whereas physiological efficiency of N, P and K was higher in INM, especially in castor.